<template>
  <div>
    <h4>第七题</h4>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(itme,index) in arr" :key="index">
        <span>{{itme['name']}}</span>
        <button @click="del(index)">买书</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(item,index) in arr"
      :key="index"

      >
        <td>{{index + 1}}</td>
        <td>{{item['name']}}</td>
        <td>{{item['price']}}</td>
        <td>{{item['count']}}</td>
        <td>{{item['price'] * item['count']}}</td>
      </tr>
    </table>
    <p>总价格为:{{allPrice}} </p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods:{
    del(index){
      // ++ 
      this.arr[index]['count']++
    },
  },
  // 计算属性
  computed:{
    allPrice(){
      return this.arr.reduce((sum,obj) => sum+=obj['price'] * obj['count'],0)
    }
  }
};

</script>
<style  scoped>
table{
  margin-bottom:50px;
}
</style>